<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>不规则投影</title>
    <link rel="stylesheet" href="../public.css">
    <style>
        .box {
            width: 100px;
            height: 100px;
            margin: 20px auto;
            background: #585858;
            background: #58a;
            background:
                radial-gradient(circle at top left,
                    transparent 15px, #58a 0) top left,
                radial-gradient(circle at top right,
                    transparent 15px, #58a 0) top right,
                radial-gradient(circle at bottom right,
                    transparent 15px, #58a 0) bottom right,
                radial-gradient(circle at bottom left,
                    transparent 15px, #58a 0) bottom left;
            background-size: 50% 50%;
            background-repeat: no-repeat;
        }
        .shadow1{
            box-shadow: 3px 3px 3px red;
        }
        .filter{
            filter: drop-shadow(2px 2px 10px rgba(0,0,0,.5));
        }
    </style>
</head>

<body>
    <div class="content">
        <h1>不规则投影</h1>
        <ul>
            <li>
                box-shoadow无效的情况
                <ul>
                    <li>半透明图像、背景图像或者border-image</li>
                    <li>元素设置了点状，虚线或半透明的边框，但是没有背景(或者当background-clip不是border-box时)</li>
                    <li>对话气泡，它的小尾巴时用伪元素生成的</li>
                    <li>切角效果、折角效果</li>
                    <li>通过clip-path生成的形状</li>
                </ul>
            </li>
        </ul>
        <div class="box shadow1 ">
        </div>
        <ul>
            <li>滤镜效果规范</li>
        </ul>
        <div class="box filter ">
        </div>
    </div>
</body>

</html>